Andrew Harding and Matt Hince team up to visit a huge man-made lake - one of New Zealand's most famous trophy trout waters - in the country's North Island: Lake Otamangakau. The shallow waters give rise to lush weedbeds, which in turn are home to huge numbers of damsel flies and damsel fly nymphs: food for hungry browns and rainbows. Can the boys capture a Big O trophy fish?